The great "warranties" that come with machines are not always all that great. The Janome "25-year warranty" is a 1-year parts and labor warranty on mechanical and electronic parts, wherein we who bought online have to send the machine to Janome. If we'd bought our machines locally, the local dealer would probably pay the labor and Janome would spring for the parts. At year 2, Janome will pay for mechanical and electronic parts, but the labor is on us, even if we bought through a dealer. The dealers would work on our machines, even if we bought online, just like they'd work on any used machine. The 3rd through 25th year is only on mechanical parts, the pieces that probably never wear out anyway. Bobbin holders and things like that aren't covered.
Buying through Costco, I used my Costco Visa which extends the manufacturer warranty for a couple years, which I assume means that electronics are covered for 2 additional years. I've used credit card warranties before and they work well! I bought a tablet computer that had issues after the formal warranty expired, and the credit card company's warranty company refunded the total price of the tablet.
Buying online comes with some risks, but the difference in price pays for a lot of shipping to Janome.